1. Field of the Invention
The present invention is in the field of signal conversion and relates to generating low-resolution signals that match high-resolution curves with much greater precision than has been heretofore obtained. More particularly, the present invention produces a high fidelity output for use with a low-resolution output device and its associated components so that the output device and its components follow the high resolution curve more accurately.
2. Description of the Prior Art
In the prior art, when it is desired to drive an output device such as a stepper motor or a digital to analog converter, which has only limited resolution, from a digital source such as a computer which has much greater resolution, it as been the practice to convert the high resolution input signal to the limited resolution of the output device and use the result to drive the output device. When, however, the variation in the signal is of the same order of magnitude as the resolution of the output device, and error may result. For example, the output of a computer is typically 2.sup.16 or 2.sup.32 counts whereas the resolution of a stepper motor is more in the range of 2.sup.8 counts. Taking a signal containing e.g., 65536 counts and reducing it to a signal containing 256 counts produces a drive signal that may not always follow the desired control signal, because of the truncation of the less significant bits of the signal. In FIG. 1 a sine curve, 10, which may be digitally generated by a computer is shown to be relatively high resolution consisting of a large number of very small steps. The conversion of the signal 10 to a low-resolution signal for use in driving and output device such as a stepper motor is shown by curve 12 and it is seen that the only times that the low-resolution signal 12 is accurate is at those points where the two curves cross such as 14, 16 and 18. At all other points the low-resolution curve is not accurate. The inaccuracy is worst at points such as 22, 24 and 26 where the low-resolution curve 12 is furthest away from the desired curve 10.